Supervisory control system



y 23,1929 R. J. WENSLEY 1,714,967

SUFERVISORY CONTROL SYSTEM Filed April 8, 1924 INVENTOR Roy J Wensley. BY

ATTORNEY Patentedlhiay 218,, 1929.

UNITED STATES PATENT OFFICE.

RO'Y- J. W'ENSLEY, OF EDGEWOOD, PENNSYLVANIA, ASSIGLl'OR '.I.O WESTINGHOUSE ELECTRIG & MANUFACTURING'COMPANY, A CORPORATION OF PENNSYLVANIA.

surnnvrsomr common SYSTEM.

Application filed April 8, 1924. Serial No. 704,997.

My invention relates to supervisory control systems and particularly to systems for controlling, from a central point or'dispatchers ofiice, remotely-disposed power appara tus.

One object ofmy invention is to provide improved signalling means for supervisory control systems that employsynchronouslymoving devices at the dispatchers office and at a remotely dis'posed station. The means 7 for controlling the synchronously-moving devices are the subject of claims in my copending application Serial No. 293,563, filed July vide means at the remote station forsignalling to the dispatcher all operations of the apparatus units under supervision, even though such operations occur before theselective apparatus has had time to function.

. Another object of my invention is to pro- 'vide improved mechanical locking means for maintaining the signalling devices at the dis patchers office and the control relays at the station in their operated positions, even though the battery that supplies the current for these devices is disconnected and reconnected.v

A further object of my invention is to provide means whereby one signalling circuit may be employed to send signals to the station to control the apparatus units, therein and the same signalling circuitmay be used for returning answer-back signals to the dispatchers oflice. t

The above and other objects of the,inven tion will be hereinafter described in con-- junction with the accompanying drawing.

In practicing my invention, I provide a sunflowers in synchronism with respect to each other. In addition, at the dispatch'ers .ofiice, a plurality of double-throw keys are provided, one for each apparatus unit at the station that it is desired to control. Further, a plurality of signalling devices are employed, two for each apparatus unit that it is desired to supervise. Also, at the dispatchers office are sources of alternating currents of different frequencies, mechanically lockmg relays for controlling the operation of the slgnalling devices and wave filters and relays that control the mechanically locking relays. At the substation, mechanically lockmg relays are provided for'controlling the operation of the apparatus units. In addi tion, sources of alternating currents of different frequencies and wave filters and controlling relays are also provided.

Referring now to the drawing, Fig. 1 is a circuit diagram of the apparatus and circuits employed in the preferred embodiment of my invention.

Fig. 2 is a modificationof-Fig. 1. Sufficient apparatus and circuits have been shown by means of the conventional diagrams to enable my invention to be readily explained and understood.

The apparatus in Fig. 1 located on the left of the dotted line is that at the dispatc'hers ofiice, while the apparatus located on the right is that at the station;

In general, the operation of my invention.

proceeds as follows By the control circuits previously mentioned, the selecting devices or sunflowers at the dispatchers office and station are operated in synchronism. When the dispatcher desires to control a particu- -lar apparatus unit, he will operate the key is resonant to the particular frequency of alternating current applied.

The operation of the relay at the substation completes a circuit for operating one of the mechanically locking relays to control the apparatus unit. By the operation of the apparatus unit, circuits areprepared whereby, when vthe sunflowers are in another predetermined position, signalling current from one of the alternating-current sources at the station will beapplied to the signalling circuit. This signalling current operates a relay in circuit with the wave filter at the ofiice, the wave filter being resonant to the particular frequency of alternating current applied.

The operation of the relay at the offiec causes the operation of one of the mechanically locking relays to change the supervisory signals to indicate the operation of the apparatus unit atthe substation. The operation ot the mechanically locking relays also opens the control circuit, thereby rendering it impossible for the dispatcher to again control such apparatus unit in the same direction. This last statement holds true even if automatic devices at the station function to control the apparatus unit in an opposite manner.

To operate again the apparatus unit, the

despatcher must restore the particular key flower 1 is provided with a motor 7 that.

rotates a shaft 8 through the medium of a clutch 9. The speed of the motor 7 is regulated by the Volta e from the current source 10 and by a centri ugal governor 11 attached to the motor. The centrifugal governorll varies the resistor 12 in the motor circuit. The shaft 8 rotates brushes 13, 14 and 15 over contact segment grou s 16, 17 and 18,

' respectively. The shaft 8 a so carries a stopnately ping device 19 having five projections or knobs 20 to 24, inclusive, thereon.

The contact segment group 17 is made up of a number of conducting and non-conducting segments. The contact segment group 18 is constructed in a manner similar to the group 17. The contact segment group 16 is made up of ten conducting segments to 34, inclusive, These segments are adapted to connect the batteries B and 13-1 alterin circuit With the brush 13 for a purpose to be described.

Magnets and 36' are associated with the stopping device 19 and carry armatures 37 and 38, respectively. The armature 37 carries a projection'39 which is positioned in the path of thestops, such as 20. The armature 38 likewise carries a projection that is positioned in the path of the stops, such as 20. The magnets 35 and 36 are relatively positioned so that, when the projection 39 engages the stop 24, the stop 40 will'be midway between the projections 21 and 22. By this arrangement, the projections 37 and 38 are alternately effective to arrest the rota-- are rotated over the contact segment groups tion of the shaft 8.

The circuits of the magnets 35 and 36 are controlled by a polarized relay 41. The conducting segments of the contact segment group 15 are connected to controlling relays in the same 'manner that conducting segment 42 is connected through an armature of a relay 43 to relays 44and 45." The relay 43 is of the ordinary type and is adapted to operate armatures 46, 47 and 48. The relay 44 controls -armatures 49 and 50. The relay carries an armature 51 that is adapted to maintain the armatures 49 and of the relay 44 in operative position when retracted. The armature 49 of the relay- 44 controls signalling devices 52 and 53. The relays 44 and 45 are controlled, through the action of the brush 15 and the conducting segment 42, by relays 54 and 55 connected in circuit with wave filters 56 and 57. The

relays 54 and 55 are alternating-current relays and respectively control armatures 58 and 59. The wave filters 56 .and 57 are resonant to predeterminedfrequencies of altermating current, such as, for example, 50 and 66. cycles, respectively.

n P ,The conducting segments of the segment group 17 extend to control relays in the same manner as the conducting segment 60 extends to an armature 61 of a relay 62. The relay 62 is of the usual type. A relay 63 is associated with the relay 62 and controls an arn'iature 64 that is adapted to lock the armature 61 of the relay 62 in an operated position. In addition, the relay 63 controls armatures 65 and 66.

The armature 61 of the relay 62 is adapted to'control the connection of springs 67 and 68 of a key K. The key K is of a two-position type and may be termed a twist key. The construction of the key K is'such that, when a handle 69 is rotated, an operating member 7 0 causes a bushing 71 to operate the springs 67, 68 and 72. When the handle 69 of this key is again rotated, the springs 67, 68 and 72 are released.

A key K1 is common to all the keys, such as K. The key K-l is of an ordinary type of a single-throw key and is adapted to operate springs 73 and 74 into engagement with their Working contacts... The spring 73 of the key Kl is connected to a generator G that generates an alternating current of predetermined frequency,'viz, 16-cycles, while the spring 74 ot-the key K-l is connected to a generator G1 that generates an alternating current of a frequency of 33 cycles.

The apparatus at the station is very similar to the apparatus at the dispatchers office. The sunflower 2 comprises a motor 107, a clutch .109 and a shaft 108-. The motor 107 is controlled by the voltage of current source 110 and by the operation of the governor 111 varying the resistor 112 in circuit with the motor. Brushes 113, 114 and 115 116, 117 and 118."

The sunflower 2 is constructed in identically the same manner as the sunflower 1 iso and the corresponding parts of the sunflower 2 have been numbered 100 higher than the parts of-the sunflower 1 to facilitate the explanation.

Relays 154 and 155 are associated with the signalingconductor 3 in circuits including -wave filters 156 and 157 that are resonant to I sunflower brush 114 and a segment such aspredetermined frequencies of alternating current, such as, for example, 16 cycles and 33 cycles, respectively. Therelays 154 and 155 are alternating current relays and are adapted to control, through the medium of the 160, relays such-as162 and 144.

The relay 162 isprovided with armatures 170,172, 173,174 and 175. The armature 175 is so positioned with respect to a relay 200 that an armature 201 of the relay 200is adapted to be held in operated position by the armature 175. In a like manner, the relay 144 is provided with armatures 203, 204, 205, 206

and 207, the armature 207 being sopo siv tioned with respect to a relay 208 that anarmature 209 thereof is held in operated position by the armature 207.

The relay 162 controls the closing coil 210 of a circuit breaker C, while the relay 144 controls the opening coil 211 of the circuit breaker C. The circuit breaker C is of'the usual type and is adapted to perform any desired function at the substation. Relays 214 and 215 are provided, respectively, with armatures 2'16, 217 and 218 and 219, 220, 221 and 223. A generator G2 is adapted to generate an alternating current'of predeter- This is shown in the modification in'Fig. 2 in which the lead from brush 115 and the lead from filters 56 and 57 are connected to line 3.

Having described the apparatus shown in the drawing, I 'will now explain its detailed operation. As mentioned before,.the motors 7 and 1-07 are energized from sources of direct current 10 and 110.- These motors are adapted to run at substantially the same speed and to drive or rotate the brushes 13 to 15, inclusive, and the brushes 113 to 115, in-

clusive. By the synchronizing circuit to be described, the brushes 13 to 15, inclusive, are rotated synchronously with the brushes-113 to 115, inclusive. These respective sets of brushes occupyv the same relative position with respect to any particular segment in the segment groups at the same time.

The speed of the motor 107 is adjusted to I be slightly faster than the speed of the motor 7. Thus, the motor 7 may be termed the controlling motor. The motors 7 and 107 are each provided with governors 11 and 111 by which they are maintained operating at substantially the same speed. v

In the normal operation of the system, the

brush 13 will engage the segment 25 slightly behind the brush 113 engaging the segment 125. Atth is time, a knob 124, carried by a stopping device 119, engages a projection 139 on an armature 137. The engagement of the projection 137 with the knob 124 momentarily arrests the movement of the brushes 113 to 115, inclusive, the clutch 109 permitting the movement of the shaft 108 to be arrested with the motor 107 operating. In this position of the brushes 113 to 115, inclusive, the brush 113 will be in engagement with the segment 125.

At the dispatchers oflice, when the brushes 13 to 15, inclusive, are rotated to this same relative position, the projection 39 will engage the knob 24 and the movement of the brushes 13 to 15, inclusive, will be momenit3 will be in engagement with the contact 25 am "a circuit will be completed extending from the negative pole ofthe battery B1 by way of segment 25, brush 13, winding of polarized relay 41, trunk conductor 6, Winding of polarized relay 141, brush 113, segment 125, positive pole of battery B4, trunk conductor 5 and to the, positive pole of the tag-Lily arrested. Simultaneously, the brush battery B.1. It will be seen that the current flow over this circuit is such that the batteries B-l and B-4 assist each other and the flow is in given directions.

' .The polarized relays 41 and 141 are thus. energized to cause the armatures 76 and 176 to engage their front left-hand contacts. a result of this operation, a circuit is completed at the dispatchers oflice extending from battery by way of armature 76 and its I left-hand contact and winding of release mag net 35 to battery. The release magnet 35 operates the'armature, 37 to withdraw the projection 39 from the path of the knob 24-,

thereby permitting the brushes 13 to 15 to be rotated.

Simultaneously, at the substation, a circuit is completed extending from battery by Way of armature 176 and its front left-hand contact and winding of release magnet 135 to battery. The release magnet 135 is operated to attract the armature 137, thereby withdrawing the projection 139 from the path of the knob 124 and permitting the brushes 113' to 115 to be rotated.

The brushes 13- to 15 inclusive, are now rotated by the motor 7 until the projection 38 engages the knob 21, whereupon the rotationof the brushes ceases. In a like manner, at the substation, the brushes rotate untiltheyare stopped by theoperation of the projection 140 engaging the knob 121. The polarized relays 41 and 141 are now operated by the batteries B and B-3 to operate their ariqo matures in the opposite direction, thereby operating the release magnets 36 and 136.

The synchronizing operation, in the event that the brushes 113 to 115, inclusive, lag behind the brushes 13 to 15, inclusive, is similar to that above described with the exception that the brushes 13 to, 15, inclusive, are those firststopped by the operation of the stopping device 19.

In the above manner, the brushes 13 to 15,

' inclusive, and the brushes 113 to 115, inclusive, are operated in synehronism.

To describe the manner in which the dispatcher controls an apparatus unit, it will be assumed that the dispatcher desires to close the circuit breaker C. The dispatcher will operate the handle 69 of key K so as to release the springs 67 68 and 72. These springs are then .in the position shown in the drawing.

The dispatcher will now operate the common control key K1.

When the brushes 14 and 15 are in engagement with the conducting segments 60 and 42, the brushes 114 and 115 at the substation will be in engagement with the segments 160 and 142. A circuit is now completed extending from the ungrounded brush of the 33 cycle generator G-l, spring 74 and its working I contact, resting contact of spring 68 and said spring, front contact and armature 61, segment 60,'brush 14, trunk conductor 3, wave 'filters 156 and-157 and relays 154 and 155 in parallel to ground.

As the wave filter 157 is resonant to the particular frequency of alternating current applied, the alternating-current relay 155 is operated and, by such operation, a circuit is completed eXtendin from ground by Way of armature 159' an its front contact, brush 114, segment 160, armature 220 and its back contact, armature 204 and its back contact and winding of relay 162 to battery.

The relay 162 is energized over the above circuit and operates to release the armature 2'01, thereby completing a locking circuit for itself. The relay 162, upon operating, also function. A pallet switch 226 on the circuit breaker C completes a circuit for the relay 215. The relay 215 operates to open the original energizing circuit of the closing coil 210 at armature 221, to complete another circuit forthe relay 162 at armature 219, and to prepare a circuit at armature 221 for the tripping coil 211 of the circuit breaker.

Another circuit completed by the operation of the relay 162 extends from the ungrounded brush of the 66 cycle generator (Jr2, winding of alternating current relay 200, front contact and armature 174, segment 142, brush 115, trunk conductor 4, wave filters 56 and 57., and relays54 and 55 in multiple to round. The Wave filter 57 is resonant to t e particular frequnecy of alternatingdeurrent applied and the relay 55 is operate c Another circuit is completed extending from ground by way of armature 59 and its front contact, brush 15, segment 42, armature 46 and its back contact and winding of relay 45 to battery. The relay 45 operatesto attract the armature 51, thereby eXtin-- ing from ground by Way of spring 72 and its resting contact, armature 47 and its front contact and winding of relay 63 to battery.

The relay 63 is operated to establish a locking circuit for itself from battery, winding 63, armature 65, spring 72 of key K to ground, to open one point in the energizing circuit of the relay 62 at armature 66 and to operate the armature 64 to ermit the armature 61 to be restored. By t e restoration of the armature 61, the previously traced controlling eircuit, extending from the 33 cycle generator G1, is opened. By the operation of the sunflower brushes, the previous signalling circuit is opened and the relay 155 at the substation is deenergized to open one point in the circuit of the relay 162. By the change in supervisory signals, the dispatcher is apprised of the operation of the circuit breaker C.

The relay 200 at the substation is energized in series with the relay 55 at the dispatchers office. The relay 200 operates to open the locking circuit of the relay 162.- The relay 162 releases its armatures, thereby opening the previously traced circuit for the relays 55 and 200. By the retraction of the armature 175 of the relay 162, the armature 201 is maintained in operated position.

It will be seen that no further controlling current is sent to the substation by reason of the key K being operatedas the relay 62 is released.

It will now be assumed that the circuit breaker C trips under the control of the associated automatic devices at the substation. As a'result of this operation, the circuit of the relay 215 is opened andthis relay is de energized.

A circuit is now completed extending from battery b way of armature 223 and its back contact, ront contact and armature 218, armature 173 and its back contact and winding of relay 144 to ground. The relay 144 operates to attract the armature 207, thereby cs tablishing a locking circuit for itself by releasing the armature 209, to complete a signalling circuit at armature 206, to open theandarmature 206, segment 142, brush 115 when it engages this contact, trunk conductor 4, wave filters 56 and 57 and relays 54 and in multiple to ground. The relay 54 is energized over this circuit and a circuit is completed extending from battery by way of armature 58 and its front contact, brush 15, segment 42, armature46 and its front contact and winding of relay 44 to ground.

The relay44 is energized over the above circuit to extinguish the lamp- 53 and to light the lamp 52 at armature 49, and to open the circuit of the relay 43. The armatures of the relay 44 are locked-in operated position by reason of the fact that the relay 45 isdeenergized. The relay .43 1s deenerglzed to prepare a circuit for the relay 45 at armature 46, to open theoriginal energizing circuit of the relay 63 at armature 47, and to prepare a circuit for the relay 62 at armature 48. By the change in supervisory signals, the dispatcher is apprised of the automatic operation of the circuit breaker C. The relay 208 at the substation is energized over the above traced signalling circuit and operates to open the locking circuit of the relay 144 at armature 209. The relay 144 is deenergized to maintain the armature 209 in operated position,.to open the signalling circuit at armature 206, to prepare a circuit for the relay 162'at armature 204 and to open one point in the tripping circuit at armature 203.

Attention is directed to the fact that, even though the supervisory signalling devices have changed, the dispatcher is not able to again close the circuit breaker C by reason of the fact that the armature 61 of the relay 62 is in a retracted position and the signalling circuit from the 33 cycle generator G1' is opened at armature 61. In order to be able to control this circuit breaker, it is necessary for the dispatcher to operate the key K to "operate the springs 67,68 and 72. In this manner accidental closing of the circuit breaker 1s prevented. By the operation of the spring 72, the locking circuit of the relay 63 is opened and a circuit is completed for the relay 62 from ground 72, upper contact, armature 66, winding 62, battery to ground. The relay 62 now attracts the armature 61, which is maintained in its operated position. After doing this, the dispatcher may close the circuit breaker O by-so releasing the key K as to release the springs 67, 68 and 72, and then op at the substation is operated. The operation of the relay 154 completesa circuit for the relay 144. The relay 144 operates to complete a circuit for the tripping coil 211 of the circuit breaker C at armature 203, to open one point in the circuit of the relay 162 at armature 204, to openthe locking circuit of the relay 214 at armature 205, to complete-a signalling circuit at armature 206 and to complete a locking circuit for itself at armature 209. The signailing circuit includes the alternating-cur rent relay 208 and therelay 54 at the dispatchers ofiice. The relays 54 and 208 perform the same functions as above described, and the apparatus is restored to normal in substantially the same manner as before described.

In the event that the circuit breaker C is closed under automatic control, the dispatch er is apprised of such operation by the energization of the relays 215 and 162, in the manner as outlined above. 1

It sometimes occurs that, after the dis. patcher closes the circuit breaker at the substation, I under overload conditions, such breaker will be immediately tripped by the action of the automatic overload or other au- 1 tomatic devices associated with it. Under such conditions, it is desirable that the dispatcher obtain an indication of such operation. The manner, in which this result is 7 brought about has been described hereinbe- 115 fore and will be but briefly outlined. The relay 162 is controlled from the dispatchers office to cause the o eration of the circuitbreaker G and to sen out the signallin current from generator G2 to operate t e relay 55 and to light the lamp'53 at the dispatchers office. When the circuitbreaker G trips under automatic control, the relay 144 is energized and signalling current from the generator G3 is sent to the dispatchers ofice, whereby the relay '54 is operated. The operation of the relay 54 causes the operation of the relay 44 and the consequent change in supervisory signals. I

It will be nderstood, of course, that the circuit operations described occur upon successive cycles of the brushes 13 to 15, inclusive, and the brushes 113 to 115, inclusive, of the sunflowers or distributers 1 and 2.

It is obvious that,while, in the present case,

j two-signalling circuits have been used, that is, those circuitsincluding the conductors 3 and 4, but one signalling circuit may be used, and it is possibleto accomplish the desired results by the use of one conductor inasmuch as different frequencies of alternating cur-' rent are usedinconnectio'n with wave filters and alternating-current relays to secure differentiation in, or selection of, the devices to be operated. a

My invention is not limited to the particular arrangement of the apparatus illustrated, butmay be variously modified without de: parting from the spirit and scope thereof, as set forth in the appended claims,

I claim as my invention:

'1. In an electrical control system, comprising a dispatchers oflice, a station and apparatusunits in said station, a first distributor at Silld'OffiCG, asecond distributor at said station, a signalling circuitextending from said ofiice to said station, andsignalling devices at said office, the combination with means for operating said two distributors in synchronism, of means including said distributors for selecting one of said 'signalling devices, a source of current, means operative when the said signalling device is selected, dependent upon the condition of one of said units, for applying said source of current to said signalling circuit, and means dependent upon the continuity of the signalling circuit for disconnnecting said source of current from.

'said circuit.. p

2. In an electrical control system,- comprising a dispatchers olfice, a station, a first dis tributor at said ofiice, a second distributor at said station, a signalling. circuit extending from said oflice to said station, and signalling devlcesat said oflice, the combination of means for operating said two distributors in synchronism, means including said distributors for selecting one of said signalling devices,

asource of current, means operative when the said signalling device is selected for applymg sald source of current to said signalling circuit, and means dependent upon the conapparatus units has changed condition, and

means operative if said apparatus unit changes condition twice durmg one revolution of said brushesfor operating said sig nalling devices at said station to indicate such changes.

4. In a'supervisory control system, a first station, a second station, apparatus units at said second station, operating means individual thereto at said first station each having a plurality of positions, synchronously rotating distributors at said first and said second stations for consecutively associating each of said apparatusunits with its inclividual operating means, means responsive to the operation of one of said operating means to one of its positions for operating its individualapparatus unit and means responsive to the operation of said apparatus unit for invariably rendering said operating means in effective while maintained in its operated position for further operation of said apparatus unit. a r

5. In a supervisory control system, a first station, a second station, automatically operable circuit breakers at saids'cond station, controlling power circuits, by said power circuits at said second station for automatically operating a circuit breaker,

synchronous'selector's at said first and said second stations, means including said synchronous selectors for selectively closing said circuit breakers, and nieans at said first station for rendering said last-mentioned means inoperative to operate\sai'd circuit breakers during a short-circuit on said power system.

6. In a supervisory control system, a first station, a second station, automatically operable circuit breakers at said second station, controlling power circuits, means responsive to a short circuit in one of said power circuits for automatically operating a circuit breaker, synchronousdistributors at said first and said second stations, means including said synchronous distributors for selectively closing said circuit breakers, and means at said first station for rendering said last-mentioned means inoperative to operate said circuit breaker during ashort-circuit on said power system.

7. In a supervisory control system, a first station, a second station, apparatus units at said second station, each-being operable to a means controlled plurality of positions, signalling devices -individual thereto at said first station, synchronous apparatus at said first and said second station for selectively associating each of said apparatus units with its individual signalling device and means for transmitting a signal for each of a plurality of operations of any one-apparatus unit which take place during a single cycle of said synchronous selector operation.

8. In a supervlsory control system, a first station, a second station, apparatus units at.

said second station operable to a plurality of positions, means for operating each of sald units to one of its positions, means for operating each of said units to its other position, means at said first station for selectively operating one of said first or said second mentionedmeans and means operative following the operation of either said first or said second means for rendering the other of said means of said unit momentarily ineffective.

9. In a supervisory control system, a first station, a second station, a plurality ofapparatus units at said second station, each of said apparatusunits being operable to a plurality of positions, an operating key individual to each of said apparatus units at said first station, each of said operating keys having a position for each of the operative positions of its individual aaparatus unit, synchronously. rotating distri utors at each of said stations, a source of energy at said first station conditioned in response to the operation of one of said keys for transmitting energy of a predetermined character to said second station, a master key common to all of said keys for rendering operative the conditioned source of energy and means including said selector at said second station responsive to said energy for operating the apparatus unit individual to said operated key to a position individual to the operated position of said key.

10. In a supervisory control system, a first station, a second station, a plurality of apparatus units at said second station, each having a plurality of positions, an operating key individual to each of said apparatus units and each operable to a position'for each position of its associated unit, a signalling line connecting said stations, a rotating distributor means for sequentially associating each of said keys to said signalling'line, a source of energy conditioned for being impressed upon said signalling line in response to the operation of one of said keys to a predetermined position, a master key commonto said keys for impressingsaid energy on said signalling line when said distributor means has associated the operated key with said line and means at'said second station responsive to said energy for operating the associated apparatus unit. 7

11. In a supervisory control system, a first station, a second station, a signalling line connecting said stations, a plurality of apparatus units at said second station each having a lurality of positions, an operating key indlvidual to each of said apparatus units and each operable to a position for each operated position of its associated apparatus unit, a distributor for sequentially associatingeach of said keys with said signalling line, a master key common to all said keys having a normal and operated position,

means including a source of energy conditioned for being impressed upon said-signallingline in response to the operation of I one of said keys to a predetermined position,

said means being operative to impress said energy on said signalling line when said common master key has been operated to its operative position and said distributors have reached a position individual to said oper atcd key, a dlstributor at said second station, a common means at sald second station con nected to said signalling line, an operating means individual to each of said apparatus mitted over said signalling line for operating the associated o crating means, andmeans responsive to tile operation of operating means for operating the apparatus unit individual to the operated key.

12. In a supervisory control system, a first station, a second station, apparatus units at said second station, an operating key individual to each of said apparatus units at said first station, rotating selectors at each of said stations, means responsive to the operation of any one of said keys including said selectors for selectively operating the associated apparatus unit, means for automatically operating said apparatus unit and means at said first station responsive to the automatic operation of said apparatus unit for rendering its associated key non-operative to restore said unit.

13. In a supervisory control system a first station, a second station, a plurality of apparatus units each operable to a plurality of positions, operating keys for each of said apparatus units, said operating keys being operable to a plurality of positions, means responsive to the operation of any one of said keys to one of its positions for operating its associated apparatus unit to a predetermined position, said means including synchronously rotated selectors at each of said stations, means at said second station for operating said apparatus unit automatically to its original position and means at said first station responsive to said automatic operation for rendering said key non-operative to again operate its associated unit to its operated position. i

y 14. I In a supervisory control system, a first station, a second station, a plurality of apparatus units at said second station, selectors at each station for selectively controlling said units from said first station, each of said apparatus units having an operated position to which. it may beoperated, a key individual to each of said apparatus units, each of said keys having a plurality of positions, means res onsive to the operation of any one of said eys to one of its positions for transmitting energy from said firstto'said second station, said means including said ,rotating selectors, means at said second station responsive to said energy for operating the associated apparatus unit toits operated position, means at said second station for automatically operating said apparatus unit to its original position and means at said first station responsive to said automatic operation of said apparatus unit for rendering said key when it is in its operated position, inefi'ective to reoperate said apparatus unit to its operated position.

15. In a supervisory control system, a first station, a secondstation, a plurality of appa ratus units at said secondstation, each of said apparatus units having an operated position .to which it may be operated,v rotating selectors for providing selective control of said units from said first station, a key individual to each of said apparatus units, each of said keys having a plurality of positions, means responsive to the operation of'any one of v apparatus unit to an operated position and means responsive to the operation of said key to its alternate position for operating said automatic responsive means to again render said key operative when in its operative position to reoperate said apparatus unit to its operative position. I

Id. In a supervisory control system, a first station, a second station, a signalling line connecting said stations, rotating. selectors at each of said stations, apparatus units each having an original position and an operative position, an operating key individual to each of said apparatus units, each having a plurality of positions, means including the selector at said first station, responsive to the operation of any one of said keys to one of its positions for lmpressing energy on said signalling l1ne at said second station, means 1ncluding the second-station selector, responsive to said energy for operating the asso- Y ciated apparatus unit to its operated position; 'means for automatically operating said apparatus unit and means at said first station re I sponsive to said automatic operation of said apparatus unit for rendering said, key none ective to impress further energy on said line.

17. In a supervisory control s stem, a first station, a second station, a plura ity of apparatus units at .saidsecond station, rotatable selectors at each station for providing selective control of said units, an operating key individual to each of said apparatus units atsaid first station, said operating key having a plurality of positions, means at said first 1 station responsive to the operation of any one of said keys for transmitting energy of a predetermined character over said selectors to said second station, means responsive to said energy for operating the associated apparatus unit, means at said first station responsive simultaneously to the operation of said key and jointly controlled by said key and said remotely disposed apparatus unlt for rendering said key non-operative to transmit v the energy of predetermined character and for simultaneously conditioning said key for transmitting energy of the opposite character for operating said apparatus unit to its original position.

' .In testimony whereof, I have hereunto subscribed my name this 31st day of March, 1921.

ROY J. WENSLEY. 

